Initial open-source release (MIT): image2api AI gateway

Full Go backend + Vue 3 frontend, OpenAI-compatible API, multi-provider
account pools, billing/admin, Docker one-command deploy with auto HTTPS.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/internal/service/session.go

@@ -0,0 +1,103 @@
+package service
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"time"
+
+	"github.com/redis/go-redis/v9"
+)
+
+type SessionPayload struct {
+	UserID    string `json:"user_id"`
+	ExpiresAt int64  `json:"expires_at"`
+}
+
+type SessionService struct {
+	client     *redis.Client
+	prefix     string
+	ttl        time.Duration
+	slideAfter time.Duration
+	slideTo    time.Duration
+}
+
+func NewSessionService(client *redis.Client, ttl, slideAfter time.Duration) *SessionService {
+	return &SessionService{
+		client:     client,
+		prefix:     "session:",
+		ttl:        ttl,
+		slideAfter: slideAfter,
+		slideTo:    ttl,
+	}
+}
+
+func (s *SessionService) Create(ctx context.Context, userID string) (string, *SessionPayload, error) {
+	token := randomUpper(48)
+
+	payload := &SessionPayload{
+		UserID:    userID,
+		ExpiresAt: time.Now().Add(s.ttl).Unix(),
+	}
+
+	raw, err := json.Marshal(payload)
+	if err != nil {
+		return "", nil, err
+	}
+
+	if err := s.client.Set(ctx, s.key(token), raw, s.ttl).Err(); err != nil {
+		return "", nil, err
+	}
+	return token, payload, nil
+}
+
+func (s *SessionService) Validate(ctx context.Context, token string) (*SessionPayload, error) {
+	if token == "" {
+		return nil, nil
+	}
+
+	raw, err := s.client.Get(ctx, s.key(token)).Bytes()
+	if err != nil {
+		if errors.Is(err, redis.Nil) {
+			return nil, nil
+		}
+		return nil, err
+	}
+
+	var payload SessionPayload
+	if err := json.Unmarshal(raw, &payload); err != nil {
+		return nil, err
+	}
+
+	ttl, err := s.client.TTL(ctx, s.key(token)).Result()
+	if err == nil && ttl > 0 && ttl < s.slideAfter {
+		// Slide the expiry, but only update the in-memory payload after Redis
+		// has actually persisted it — otherwise a failed Set would leave the
+		// returned ExpiresAt out of sync with what's stored.
+		renewed := payload
+		renewed.ExpiresAt = time.Now().Add(s.slideTo).Unix()
+		if updated, marshalErr := json.Marshal(&renewed); marshalErr == nil {
+			if setErr := s.client.Set(ctx, s.key(token), updated, s.slideTo).Err(); setErr == nil {
+				payload.ExpiresAt = renewed.ExpiresAt
+			}
+		}
+	}
+
+	if payload.ExpiresAt <= time.Now().Unix() {
+		_ = s.Destroy(ctx, token)
+		return nil, nil
+	}
+
+	return &payload, nil
+}
+
+func (s *SessionService) Destroy(ctx context.Context, token string) error {
+	if token == "" {
+		return nil
+	}
+	return s.client.Del(ctx, s.key(token)).Err()
+}
+
+func (s *SessionService) key(token string) string {
+	return s.prefix + token
+}